Here at Political Calculations, we occasionally generate some really interesting charts and data as we work on other projects behind the scenes. With that in mind, we've tapped the U.S. Census' income data going back to 1947 showing the average income earned by individual men and women in the U.S., and also the combined average income for all individual Americans.

What makes the chart somewhat more interesting is that it captures the changing distribution of the U.S. work force by sex over the years, which we can see in the relative placement of the combined mean income line with respect to the lines for men and women.

Starting in 1947, we see that there were more than 2 men for every 1 woman in the work force at that time. That was changing rapidly however as the relative number of women in the U.S. workforce grew steadily until 1979, when women slightly outnumbered men in the U.S. work force for the first time.

And for that matter, every year since 1979 as well! Overall, the U.S. workforce has been very nearly equally balanced by sex since that time, with women peaking at 51.13% of the U.S. work force in 1988. In 2010, the percentage of women in the U.S. work force was 50.2%, just barely over half.

It's also interesting to note that since 1947, the annual average income earned by all individual women has nearly tripled, while the income for men has increased by a factor of 2.1. Meanwhile, the average income earned by all Americans has gone up by slightly less, doing just better than doubling in value during the time from 1947 to 2010.

That's largely due to the greatly increased number of women working today as compared to 1947, combined with their generally lower incomes. Although women's incomes have risen much more quickly than men, their greater numbers in the work force combine with their lower incomes overall to produce the result where average income in the U.S. has grown more slowly than it has for either men or women separately.